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MONDAY, June 17, 2013 — Serious autoimmune diseases and infections are a detriment to your mental health, according to a new study in The Journal of American Medical Association (JAMA) that found 45 percent of people with serious infections are likely to suffer from depression. The report also says that the risk of developing a mental illness is 62 percent higher for people who have had serious infections than those who did not have a serious infection.

The study was headed by Michael Eriksen Benr's, MD, PhD, a senior researcher at National Centre for Register-based Research, Aarhus University Mental Health Centre Copenhagen, Copenhagen University Hospital, Denmark, with data drawn from the Danish longitudinal registers. Researchers followed a total of 3.56 million people born between 1945 and 1996 from January 1, 1977 through December 2010. Of that group, 91,637 had been seen in the hospital for mood disorders.

The study looked at mood disorders that occurred during treatment and those surfaced after treatment.

"We included all types of hospital contacts with infections, except HIV/AIDS," Dr. Benr's said. "All included types of infections that were associated with an increased risk of mood disorders; however, sepsis (infection in the blood), hepatitis infection (infection in the liver) and urogenital infections were associated with the most elevated risk of mood disorders."

"In total, we studied 30 different autoimmune diseases that were included in the registers," he said, noting that autoimmune hepatitis, systemic lupus erythematosus, celiac disease, multiple sclerosis, Type 1 diabetes and psoriasis were some of the autoimmune diseases associated with the most elevated risk of subsequent mood disorders.

Benr's explained infectious diseases and inflammation can affect the brain through several pathways:

"Infections and inflammation can increase the permeability of the blood-brain barrier that protects the brain, making the brain more vulnerable to immune components or other substances in the blood."

"Some infectious agents can also invade the brain directly. And peripheral nerves can also be affected by inflammation and thereby affecting the brain."

"The gut microbioma may also be affected by infections or the possible medical treatment, which may have an effect on the mind as well."

He said that the researchers' findings support results from smaller studies suggesting that immune responses may affect the brain in ways that increase the risk of mood disorders.

Amesh A. Adalja, MD, FACP, clinical assistant professor in the department of Emergency Medicine and adjunct instructor in the division of Infectious Diseases at the University of Pittsburgh Medical Center, said that the study supports what clinicians in infectious disease see all the time:

"It confirms what we know, that any time a person experiences a serious illness there are repercussions that continue to affect patients even after they recover from the acute illness," he said. "And we've known that people who have septic shock which is sort of an end stage of many infectious diseases, bacteria or viral have a lot of mental and emotional problems that occur after their infection."

What is the Physiological Process?

Dr. Adalja explained that the immune system is compromised in these infectious diseases and the body cannot protect itself, and sometimes fights itself, impacting brain chemistry and leading to depression.

"When you have an infection or an immune disorder, the immune system is turned on — whether it's by infection or because it's attacking itself from an autoimmune disease — a lot of inflammatory molecules are secreted as the body is ramping up its defenses," explained Adalja. "Those molecules work on taking care of the infection and when they do take care of the infection that creates inflammation — redness or fever or swelling. Those are all markers of immune activation occurring. They also have some ability to alter brain chemistry. They can produce alterations of your brain chemistry and that's how you get depression. "

In addition, some treatments for infectious diseases are known to cause depression but treatment cannot be stopped or altered, so mood disorders must be treated after the infection infection is treated and once the medical crisis has subsided.

"For example, in Hepatitis C we treat Hepatitis C with the drug Interferon," said Adalja. "Interferon is a natural substance that's produced by your body but we administer it exogenously for the treatment of hepatitis C and it helps clear the virus from the body. And depression is a well-known side effect of interferon therapy. You actually have to screen people before you put them on interferon. And during treatment to look for signs and symptoms of depression that may be occurring because of the interferon. There are even cases of people committing suicide on Interferon. "

Researchers Say Cause is Not Clear

Benr's said it is still unclear to researchers exactly what the connection is between infectious disease and the brain, and why it might lead to mood disorders. Underlying genetic, psychological, or non-immune-related mechanisms must be considered. "Previous research has shown that there seem to be a bidirectional relationship between the immune system and the brain, where psychological stress for instance can make a person more likely to acquire infections," he added.

Adalja points out that being sick can also wear people down physically and emotionally.

"When a sickness hits a certain threshold it puts someone at a risk factor for depression," Adalja said. "Depression can also be triggered by a significant life event. And serious illness is a significant life event."

"The other factor is either a biological mechanism," he said. "We know that they are in critical illness and during severe infectious disease the body's immune system releases a lot of different substances in order to combat the infection. Some of these side effects of those molecules may be to affect the brain chemistry in such a way that they are more likely to have depression. "

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